The present invention generally relates to optical fiber closures and, more particularly, to an optical fiber closure having improved optical fiber capacity and insertion loss characteristics.
Optical communications refer to the medium and the technology associated with the transmission of information as light pulses. Many applications utilize an optical fiber network to establish optical communications between network locations. In order to enable optical communication and the flow of optical signals between network locations, various interconnections must be established between different optical fibers.
FIG. 1 depicts a fan-out device 100 associated with the prior art for handling optical fibers. Specifically, fan-out device 100 accepts a ribbon cable 102 which comprises a plurality of individual optical fibers 104. Such devices are used to separate the individual fibers 104 prior to their terminations onto optical connectors. A typical ribbon cable consists of 12 individual fibers. As these individual fibers are separated, they are subject to bending. The bend radius RB of the fibers is an important characteristic of the fan-out device because it corresponds to the degree of xe2x80x9clight leakagexe2x80x9d in each of the individual fibers. That is, as light propagates through an individual fiber, a portion of the light will travel beyond the boundaries of the fiber if RB is too small (corresponding to an angle of incidence of the light upon the fiber core that is greater than the critical angle for total internal reflection of the light). Current designs have RB of approximately 0.5 inches which results in unnecessarily high leakage of light and optical signal degradation.
Additionally, current fan-out devices comprise a two piece construction with an epoxy seal. Specifically, upper portion 106 and lower portion 108 are joined to protect the individual fibers 104 as they fan out. The epoxy is utilized to maintain an RB so that if a fiber is pulled, it will not kink and generate microbends. If this epoxy cures while the fiber is not set to the correct RB, optical losses will result from this condition also. Moreover, as the upper portion 106 and lower portion 108 are joined, there may be alignment errors that cause severing or crimping of one of more of the individual fibers.
These and other deficiencies of the prior art are overcome according to the principles of the invention in an apparatus for fanning out an optical ribbon cable having a top cover portion, a fan-out portion and a bottom portion such that the three portions are formed as a unitary body with the fan-out portion having a stacked array of optical fiber guides for housing individual fibers of the optical ribbon cable. The top cover portion is connected to the fan-out portion by a first hinge and the bottom cover portion is connected to the fan-out portion by a second hinge. In one embodiment, the first hinge and second hinge are of the same material as the top cover portion and bottom cover portion. The material of which the apparatus is comprised is a substantially non-opaque material and in one embodiment on the invention is a polymer 12-based material.
A part of the fan-out portion transitions to a hook member. Additionally, a part of the top cover portion transitions to a partial tang and the bottom cover portion transitions to a partial tang to jointly define a complete tang. The hook member and complete tang facilitate securing the apparatus to a support structure.
The top cover portion has a plate projecting perpendicularly from a top cover portion front face and the bottom cover portion has a plate projecting perpendicularly from a bottom cover portion front face. The two plates secure a ribbon cable in an axis extending longitudinally through the fan-out apparatus. The fan-out portion of the apparatus is so configured that a first portion of the arrayed guides is co-linear with the longitudinally extending axis, a second portion of the arrayed guides is above the longitudinally extending axis and a third of the arrayed guides is below the longitudinally extending axis. The fan-out portion has a body having a front face and a rear face. The arrayed guides traverse longitudinally through the fan-out portion from the front face to the rear face. In one embodiment of the invention, the arrayed guides are in the form of a 3xc3x978 matrix in the body. The arrayed guides are tapered such a width of each of said guides at the front face is wider than a width at the rear face. The fan-out apparatus also has an apparatus front face wherein the arrayed guides define pathways for individual optical fibers disposed from said apparatus front face to said fan-out portion rear face having a bend radius of at least approximately 1.5 inches.